An optical designer is often times faced with the challenge of designing an optic that receives near collimated light rays from a Fresnel lens or parabolic reflector and creating a diffuse beam that has a precisely diverging beam while maintaining a round beam shape. An efficiency requirement is specified for the output beam.
Conventionally, concave or convex spherical impressions can be milled or machined by electronic discharge into the face of an injection mold tool. Depending on the pattern of the impressions the resultant beam pattern might vary from square, diamond or hexagonal shapes. Alternatively, to create a round beam shape the designer could settle for a substantial amount of non-diffused collimated light in the resultant optical pattern. Other approaches use sandblasted, chemical and/or laser etched holographic surfaces to obtain a round beam pattern. These conventional approaches can have low efficiencies caused by over-scattering the light rays, or come at a premium cost (e.g., holographic surfaces).